Underground Atomic Bomb Test

On November 29, 1951, the first underground atomic bomb testing occurred when
the 1.2 kiloton Buster-Jangle Uncle was detonated 17 feet below ground level in
Nevada. Underground detonations began as a way to reduce the cost and risk of
testing atomic weapons. Before 1951, many atomic bombs were detonates on islands
in the Pacific Ocean, but this was costly and still ran the risk of residual
radioactive material contaminating the atmosphere. By detonating atomic weapons
underground, explosions may not introduce these radioactive materials into the
atmosphere and tests were less costly because they could occur within the United
States. When the bomb Uncle was detonated, it created a cloud that was 11,500
feet high and a crater that was 260 feet wide by 53 feet deep. With underground
atomic testing, the amount of radioactive material released depends on how deep
the bomb is located. If the bomb explodes at a sufficient depth, then the test
is contained. However, radioactive material can “seep” out of a contained
radioactive chamber created by an explosion, so these tests must occur in
isolated locations and be monitored for any changes in radiation levels. The
Threshold Test Ban Treaty, signed in 1974 by the United States and Soviet Union,
banned the underground detonation of bombs greater than 150 kilotons. While
underground testing has not comprehensively banned, the International Monitoring
System keep track of underground detonations throughout the word.